1. Technical Field
The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
2. Description of the Related Art
The demand for inverters used in robots, air conditioners, machine tools, and the like, industrial electronics which are represented by an uninterrupted power supply for office machine, and small-sized power converters, is rapidly increasing. It has been gradually important in these power converters that the apparatus has a smaller size and a lighter weight, a higher efficiency, and a lower noise. However, these requests are difficult to simultaneously satisfy by only power semiconductor devices of the prior art, such as, a bipolar transistor, a high power MOS field effect transistor (MOSFET), or the like. Therefore, an insulated gate bipolar transistor (IGBT), which is a semiconductor device retaining both of high-speed switching characteristics of the high power MOSFET and high power characteristics of the bipolar transistor, has received attention. A trench structured IGBT has a structure where a plurality of trench grooves are formed to promote a high withstand voltage and a gate insulating film and a gate electrode are disposed within the trench (U.S. Pat. No. 5,801,408).